Metals like aluminum, gold and tungsten are used to create conductive layers
on a device. They are generally applied with two different methods, evaporation
and sputtering, grouped into the category of "physical vapor deposition",
or PVD.

Evaporation uses heat (either an electric filament or an electron beam)
and high-vacuum (between 5x10-5Torr and 1x10-7 Torr) to
vaporize the metal source. The evaporating source material condenses on the surface of the cooler
wafers which are held in a semispherical or "planetary" arrangement
over the source.

Sputtering uses a cathode to create an argon
plasma which bombards the source metal. The dislodged metal molecules
are focused by a "lens" of radiation-absorbent material, called a collimator, and deposited in a thin film on
the surface of the wafer.